"tonight" is the 29th single released by YUKI. It was released two versions: a limited CD+DVD edition and a regular CD edition. The title track was used as the theme song for KADOKAWA produced film Grasshopper, originally written by Isaka Kozaro. "tonight" was produced by YUKI and agehasprings. The single reached #11 on the weekly Oricon chart, and it continued to rank for a total of five weeks.